Sugar Ray Robinson is, without question, the greatest fighter who ever lived. He was 128-1-2 before he suffered his second defeat, and he beat enough Hall of Famers to fill a football team.

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The thing that Robinson, and more recent superstars such as Sugar Ray Leonard, Roberto Duran and Marvelous Marvin Hagler, had over Mayweather was elite opposition.

"Let me tell you this right here about the boxing game," Mayweather's father, Floyd Sr., said. "There were much better fighters when Sugar Ray Robinson was coming along. There were much better fighters when Joe Louis was coming along. But that's not my son's fault. My son beat who's here today, and if they can't protect themselves, oh well."

Mayweather fought most, though not all, of the best of his era. He missed Kostya Tszyu when he was at 140 pounds and to this point, he hasn't fought Manny Pacquiao.

But he's reeled off 44 in a row and, in truth, none of them were close. He routed Guerrero on Saturday, connecting on an incredible 60 percent of his power punches while holding Guerrero to just 19 percent overall.

Guerrero had some success in the first two rounds in trying to pin Mayweather along the ropes, where he could maul him. All three judges gave Guerrero the first round for that. But that was it.

Love him or hate him – there is usually no in-between – Mayweather always figures it out. He's a boxing savant and has been since the first time he pulled on gloves as a child in Grand Rapids, Mich.

Mayweather, who was extraordinarily classy and respectful at the post-fight news conference, took the high road when he was asked where he'd rank himself.

Prior to the fight, he declared himself the best who ever lived. He backed off that on Saturday.

"I take my hat off to Sugar Ray Leonard and all those other fighters who paved the way for me to be where I am at today," Mayweather said. "I'm not here to match myself against them because, like I said before, I'm not in their era. I respect them. I take my hat off to them. But I'm in my era, and I just do what I do."

It's unfortunate that he hasn't had those kinds of rivals. The Pacquiao fight fell through for a myriad of reasons, despite intense interest from the fan base.

But other than Tszyu and Pacquiao, there aren't a lot of elite fighters that he hasn't faced. He's beaten at least four guys who figure to wind up in the International Boxing Hall of Fame – Arturo Gatti, Oscar De La Hoya, Shane Mosley and Miguel Cotto – and may have several more victims who sneak in.

He's planning to fight on Sept. 14, the first time in about a dozen years that he will have fought twice in four months. He brushed aside questions about Canelo Alvarez, who is probably the biggest threat he faces.

Adrien Broner is the only boxer who is in the same realm with Mayweather in terms of physical gifts, and he's just moved to welterweight, Mayweather's division.

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But when Broner was asked about a potential fight with Mayweather, his good friend, he made an obscene gesture with both hands.

Any other fighters who might face Mayweather, guys like Amir Khan, Danny Garcia, a potential rematch with Victor Ortiz, would be massive underdogs.

He is so astute, he knows when he needs to adjust, and he did that by bringing his father back to train him. His father taught him the game and helped build him into a fighting machine. He also made him one of history's foremost defensive boxers.

After his 2012 win over Cotto, Mayweather knew he had to fix things.

"Miguel Cotto hit me with some shots I shouldn't have been hit with, so I had to bring the defense master back, my father," Mayweather said as his father, seated a few feet away, beamed.

The elder Mayweather was mortified when he first resumed working with his son and saw bigger fighters, who in the past would have never laid a glove on his son, tagging him with clean shots.

He knew they needed to do some work, and to Floyd Jr.'s credit, he was willing to do what he needed to do.

"I got in his ear and started telling him he can't take no more punches like that," Mayweather Sr. said. "In two days, he wasn't taking those punches any more. He started capitalizing and countering. As we went along, he kept making them miss and then capitalizing. He just got better and better."

He's done that throughout his career, and that's why he is unquestionably the best of this time. But his lack of opposition will never allow him to be compared to guys like Robinson, Henry Armstrong, Muhammad Ali and the sport's other super elite.